1. Field of the Invention:
The invention is directed to a three function control mechanism for controlling the positioning of three separate hydraulic control valves through the manipulation of a single control lever that is operatively mounted to a main ball joint.
2. Description of the Prior Art:
In operating work vehicles, such as crawler dozers, the operator controls a plurality of work operations through manipulating various control levers that control the positioning of hydraulic control valves and thereby the flow of hydraulic fluid to the hydraulic cylinders. It is desirable to control a number of the related operations from a single control lever. Typically three-function control levers have a T-bar shaped control handle that can be moved through two orthogonal control arcs to operate the first two functions and twisted to control a third functions. It is desirable that the control lever can be manipulated to operate each of the functions independently or in unison with the other functions.
Such control three-function control levers are used on crawler dozers manufactured and marketed by the assignee of the present application, for controlling the positioning of the working blade. These control levers are operatively coupled to the machine by a series of universal joints which permit the three-function movement. U.S. Pat. Nos. 3,131,574 and 3,388,609 assigned to the assignee of the present patent application, disclose similar multifunction control lever mechanisms for work vehicles.
A ball joint mounted three-function T-bar control lever has also been proposed in U.S. Pat. No. 4,187,737. In this patent the control lever is secured to a ball socket that is operatively coupled to a ball that is mounted through a stud to the frame of the vehicle. Two of the functions are controlled by moving the control lever through two orthogonal control arcs whereas the third function is controlled by twisting the control lever. In this patent a lost motion coupling is provided to isolate the third function control assembly from interference when the other functions are manipulated by the control lever. PG,4
U S. Pat. Nos. 3,321,990, 4,489,805 and 4,526,055 disclose other multifunction control mechanisms for work vehicles.